18F-FLT uptake in human colorectal cancer cells in relation to early response to radiation therapy:an in vitro study / 中华核医学杂志

ABSTRACT

Objective To evaluate whether 18F-fluorothymidine(FLT) can be used to monitor early response to irradiation in colorectal cancer (CRC).Methods SW480 cells were cultured and irradiated with 0, 10, and 20 Gy.Twenty-four hours later, morphological changes, apoptosis, necrosis, proliferation,and cell cycle phases were observed.Uptake of 18F-FLT was measured in these tumors in vitro from 24 h to 72 h after irradiation.The one-way analysis of variance was used to analyze the data.Results Apoptotic and necrotic cells were detected 24 h after radiotherapy.SW480 cells proliferation was significantly delayed after irradiation in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylte-trazolium bromide (MTI) assay.Cell cycle analysis showed that SW480 cells had a decreased fraction of cells in S phase( from 33.23% to 9.24%,then to 5.43% ) and an arrested fraction in G0-G1.After SW480 cells were cultured for60 min, the uptake of 18F-FLT was (5.21 ± 1.60) %; and 24 h after irradiation of 10 Gy, the uptake decreased significantly to (4.27±0.48)% (F=8.253, P=0.009).And 72 h after irradiation, the uptake further decreased significantly to (3.39 ± 0.59) % ( F = 36.715, P＜0.001 ).In tumor tissue, the uptake of 18F-FLT reduced significantly 72 h after radiotherapy (10 GyF = 12.388, P = 0.007; 20 GyF = 16.744, P = 0.004) and the attenuation degree increased with the radiation dose.Conclusion The uptake of 18F-FLT in SW480 cells or in CRC could reflect the changes of SW480 cells in proliferation, cell cycle re-distribution, cell apoptosis and necrosis.The results suggest that 18F-FLT may be used for monitoring early response to irradiation of CRC.